Tailor-made double-face imprinted membrane with ultra-high specific surface area asymmetric structure through a connective method of dip-coating and delayed phase inversion for selective adsorption of cadmium ion

Aiming at the increased cadmium ion (Cd²⁺) concentration in drinking water that endangers environment and human being, an emerging cadmium ion imprinted membranes (Cd-IIMs) with double-face asymmetric structure is prepared by loading MWCNTs on the both surfaces of membrane based on dip-coating and delayed phase inversion. The intercalation of high specific-surface-area MWCNTs onto membrane surface can not only enhance the loading in unit area of membrane, but endow the membrane with appreciable stability in continuous operation and some extreme environment. Accordingly, the rebinding capacity of Cd-IIMs can reach up to 162.44 mg g⁻¹ toward Cd²⁺. Importantly, it work well even for high-level concentration of interferents and show a high selectivity factors (2.20 for Zn²⁺, 2.53 for Pb²⁺, 2.72 for Ni²⁺, 2.94 for Fe³⁺, 2.12 for Na⁺, 1.98 for K⁺, 2.24 for Ca²⁺ and 2.26 for Mg²⁺). Then, influencing factors to stability in low temperature, strong acid and strong alkali environments are also discussed based on the different work environments. The rebinding capacity of Cd-IIMs still maintain about 94.0% of the original result after 10 adsorption-desorption cycling, which prove its appreciable regeneration performance. Thus, the Cd-IIMs enlightened a promising prospect for the selective removal of heavy metal ions wastewater.